<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="test"></div>


    <!-- 引入react核心库 -->
    <script type="text/javascript" src="../js/react.development.js"></script>
    <script type="text/javascript" src="../js/react-dom.development.js"></script>
    <script type="text/javascript" src="../js/babel.min.js"></script>

    <script type="text/babel">  /*此处一定要写babel*/
        //创建组件
        class Life extends React.Component{

            state={opacity:1}

            death = ()=>{
               

                //卸载组件
                ReactDOM.unmountComponentAtNode(document.getElementById('test'))
            }

            //组件挂载完毕之后
            componentDidMount(){
                this.timer =  setInterval(() => {
                    //获取原状态
                    let {opacity} = this.state
                    //减少幅度
                    opacity -=0.1
                    if(opacity <=0){
                        opacity = 1;
                    }
                    //设置新透明度
                    this.setState({opacity})
                }, 200);
            }

            //组件将要被卸载的时候调用
            componentWillUnmount(){
                //清除定时器
                clearInterval(this.timer)
            }

            //render调用的时机 初始化渲染 状态更新之后
            render(){
               

                return(
                    <div>
                        <h2 style={{opacity:this.state.opacity}}>React学不会怎么办?</h2>
                        <button onClick={this.death}>不活了</button>
                    </div>
                )
            }
        }

        //渲染组件到页面
        ReactDOM.render(<Life/>,document.getElementById('test'))
    </script>

    
</body>
</html>